F4U-1 Structural Framework

[Ambaryerno]

So what I THINK I'm really needing is stuff like this:

And then a guide for which bulkhead/rib goes where so I can position them in the right spot. I can then use that to "skin" the model.

 

[cvairwerks]

You need to drill down a little further. What's that drawing number?

 

[Ambaryerno]

Drawing number is 10256.

 

[cvairwerks]

Pop over to 13881 and you can get enough IML points to plot the curves. In this case, it will be a mirror between the 13881-1 and -2. Just watch that the bottom of the web has a funny shape right at the bottom center line. No need to model it, but be aware. Don't know the skin thickness, but for gaming the IML is close enough. You won't see a .030" to .049" thickness difference in the surfacing, unless you have something poking out. BTW, the drawing title gives you a good approximation of the bulkhead location....186" from the datum line.

The armor plate is 13888 and the formers that go with it are 13887.

 

[Ambaryerno]

Sorry, I'm just not following what I should be doing with this. My approach would be to screenshot it, rotate it until it's as close to true as I can, and use it as a background image, but that doesn't seem to be what you're suggesting. I'm not sure how I get IML points or whatever from this.

 

[cvairwerks]

IML is the surface of the structure, without the skin. If you are building the airplane bulkhead by bulkhead, you would create this part and then place it in the model at the appropriate location. In this drawing, the curves on the part are not defined by radii and locations, but rather by particular points defined by X and Y coordinates. You would place the points in the model, then connect them with a set of arcs. Same way your would draw the part on paper, just doing it in the computer. Once you have the part outline drawn, you would place it in the model, at 186" from the datum. This is just like building a stick model on the bench, but you are doing it in the computer.

Screenshotting is not a very accurate way to develop the part. You have no idea as to how big the original drawing was, if it was scaled, what reduction was used during microfilming and how much if any variance there was in the original drawing due to humidity and so on. The only drawings you can count on being accurate to within the listed tolerances, are Mylars, and in this case I don't think they exist anymore. You can only be sure if you redraw the part using the listed dimensions.

 

[Ambaryerno]

So...basically like this (which is how I'd modeled what I had in the first place, I just wasn't using the actual Vought drawings).

 

[Ambaryerno]

And if I wanted to, I could model the actual bulkhead itself, not just the outline.

(Seeing as this one would be visible from the cockpit view, I probably would want to).

 

[bse7entn]

My workflow is a blend of what both of you described. What cvairwerks described is most applicable to a CAD workflow for fabrication. With a polygonal workflow you have to use the given dimensions and make exceptions where it makes sense for optimization. Especially important for real time applications.

For some parts I have actually CAD modeled them to bring into Blender. Partly for CAD practice, part because cast parts aren't fun to polygon model, and in some instances parts have been fabricated from my CAD.

 

[Ambaryerno]

Well, I don't use CAD so I think this is the workflow I'll need to stick with.

 

[Ambaryerno]

So here's a question, what do you do when you hit a discrepancy in the plans like this:

So, section B-B on the former is shown to angle slightly down, while the other two angle slightly up.

However, when you look at it in place on the assembly:

It's shown angling UP. While I can see discrepancies with the parts not quite scaling exactly from drawing to drawing (which I've found to be the case when overlaying the sketches for modeling) the fact that a part has a completely different shape altogether is another matter. Which one do I go by? The individual part, or the part as drawn in-situ?

 

[bse7entn]

You go by the individual part sheet because that's giving you the dimensions of that part.

This could be a case where the assembly drawing is older and is showing an older part and instead of drawing a whole new sheet, they just update the notes or part call outs.

Also there are errors on sheets. Don't be shocked when you find them.

 

[Ambaryerno]

You go by the individual part sheet because that's giving you the dimensions of that part.

This could be a case where the assembly drawing is older and is showing an older part and instead of drawing a whole new sheet, they just update the notes or part call outs.

Also there are errors on sheets. Don't be shocked when you find them.

It'd be nice to find photos of the finished bulkhead assembly to compare to. I've got some of one that's partially assembled but the formers aren't in place.

 

[bse7entn]

If you're on facebook look up Vultures Row Aviation's photos. Might have what you're looking for.

 

[Ambaryerno]

If you're on facebook look up Vultures Row Aviation's photos. Might have what you're looking for.

I already checked out their gallery and website and sent them an email.

 

[MIflyer]

 

[MIflyer]

View: https://www.youtube.com/watch?v=5R5TtB86Vik

 

[MIflyer]

And also:


View: https://www.youtube.com/watch?v=CanLZ2Ysk_o

 

[Simon Thomas]

#36. The Centaurus was the first 2,000 hp engine, type tested in Oct 1938. The R-2800 first achieved 2,000 hp when type tested in Sept 1939.
I am not 100% sure of the dates, but I know someone will correct me.

 

[J_P_C]

Bse7entn can be more help than I, on doing the 3D stuff. The last time I did any, was on Mechanical Desktop 3.0 and Catia 5, probably 25 years ago.

- CATIA V5 25 years ago - are you sure about this???